I just played my first VASSAL game on the server with an opponent. We had a few problems that might be ameliorated a bit by some additions to the core code for VASSAL:
There is NO feedback on connection quality. We had a few times where the die rolls I was making were not showing up for my opponent. Fortunately, we had a Skype connection, so he was able to detect the problem while I was giving a “play by play” call on a series of die rolls. After we figured out that we needed to re-synchronize, eventually we got back on track. However, it would be nice if one could see a connection quality light with green/amber/red, and could see if his connection to the server were of poor quality, or intermittent (or solid, as well!).